Mobile communication systems were developed to provide mobile users with communication services. With the rapid advance of technologies, the mobile communication systems have evolved to the level capable of providing high speed data communication service beyond the early voice-oriented services.
Recently, standardization for a Long Term Evolution Advanced (LTE-A) evolved from LTE, as one of the next-generation mobile communication systems, is underway in the 3rd Generation Partnership Project (3GPP). The term ‘LTE system’ as used herein may be construed to include the legacy LTE system and the LTE-A system. In order to improve the performance of such systems, discussions are being held on a variety of schemes. The discussion on the Multiple-Input Multiple-Output (MIMO) is also continued. MIMO is a technology to improve transmission efficiency by transmitting data using a plurality of antennas.